Display device and driving method therefor

Abstract

When a display mode is a high-resolution mode, image display is performed by time division driving. When the display mode is a low-resolution mode, image display is performed by defining j pixel circuits arranged continuously in a direction in which scanning signal lines extend as one group, bringing only one organic EL element into a light-emitting state in each of the pixel circuits in a frame period, and bringing organic EL elements having respective light emission colors different from one another into a light-emitting state in the j pixel circuits included in each group in the frame period. Pixel circuits in a display unit are configured such that the intervals of organic EL elements which go into a light-emitting state in the frame period when in the low-resolution mode are equalized regarding a direction in which the scanning signal lines extend.

Description

TECHNICAL FIELD[0001]The present invention relates to a display device and more particularly to a display device including self light-emitting type display elements which are driven by a current, such as an organic EL display device, and a method for driving the display device.BACKGROUND ART[0002]Conventionally, as display elements included in a display device, there are an electro-optical element whose luminance is controlled by a voltage applied thereto, and an electro-optical element whose luminance is controlled by a current flowing therethrough. A representative example of the electro-optical element whose luminance is controlled by a voltage applied thereto includes a liquid crystal display element. On the other hand, a representative example of the electro-optical element whose luminance is controlled by a current flowing therethrough includes an organic EL (Electro Luminescence) element. The organic EL element is also called an OLED (Organic Light-Emitting Diode). An organic...

AI Technical Summary

Benefits of technology

[0091]According to the first aspect of the present invention, intervals of electro-optical elements which go into a light-emitting state in each unit frame when in the low resolution mode is equalized regarding a direction in which the scanning signal lines extend. Accordingly, occurrence of display unevenness (color unevenness) or vertical stripes is suppressed, and an image with which viewers do not feel uncomfortable is displayed.

[0092]According to the second aspect of the present invention, when a low resolution image is displayed, j pixel circuits are defined as one group, and electro-optical elements having respective light-emitting colors different from one another are brought into a light-emitting state in j pixel circuits included in each group. Hence, a color image with a resolution not more than 1 / j of a resolution in the time-division driving can be displayed by one vertical scanning. In this way, in a display device that adopts the time-division driving, it is possible to display a low resolution image while lowering the driving frequency. Accordingly, by switching, depending on the magnitude of demand regarding a definition of a display image, for example, the display mode between a high resolution mode, in which a high resolution image is displayed by the time-division driving, and a low resolution mode, in which a low resolution image is displayed by a driving method whose driving frequency is lower than that of the time-division driving, power consumption can be reduced compared to that in a case where image display is always performed by the time-division driving. Moreover, when in the low resolution mode, momentary luminances of the electro-optical elements do not need to be increased compared to those in a case where the time-division driving is performed. Thus, shortening of the lifetime of the electro-optical elements is suppressed. As described above, in a display device that adopts the time-division driving, it is possible to reduce power consumption over the conventional one while suppressing shortening of the lifetime of elements without causing a display defect.

[0093]According to the third aspect of the present invention, when the display mode is the low resolution mode, pause driving is performed where a refresh period during which writing of image data is performed and a pause period during which the writing of image data is stopped are repeated. Accordingly, power consumption of peripheral drivers (drive circuits which are provided in a peripheral region of the display unit to allow the pixel circuits to operate) can be greatly reduced compared to that in a case where image display is always performed by the time-division driving. In this manner, in regard to reducing power consumption, an extremely remarkable effect is obtained.

[0094]According to the fourth aspect of the present invention, electro-optical elements having respective light-emitting colors different form one another can be brought into a light-emitting state in j pixel circuits included in each group by selecting one of j light-emission control lines corresponding to each row. Hence, power consumption resulting from driving of the light-emission control lines when in the low resolution mode becomes very small.

[0095]According to the fifth aspect of the present invention, the occurrence of bias in the levels of degradation of transistors and degradation of electro-optical elements in each pixel circuit is prevented.

[0096]According to the sixth aspect of the present invention, as with the fifth aspect of the present invention, the occurrence of bias in the levels of degradation of transistors and degradation of electro-optical elements in each pixel circuit is prevented.

Problems solved by technology

An organic EL display device adopting the passive matrix system is simple in structure, but is difficult to achieve size increase and definition improvement.

According to the configuration shown in FIG. 50, since many circuit elements are required within a pixel circuit, it is difficult to achieve definition improvement.

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